The invention is in the field of fluorescent lighting fixtures. It is particularly concerned with a multi-lamp fluorescent fixture incorporating a reflective assembly in place of a fluorescent lamp to increase the lighting efficiency of the fixture within the remaining lamps.
Fluorescent lighting lighting fixtures have been and are extensively used in office, factory and residential lighting. The most popular type of fluorescent is the four-lamp two-ballast (transformer) fixture. It has been estimated that there are over one billion such fixtures installed in the United States and between 100 and 200 million are manufactured annually. The four-lamp two-ballast fixture is manufactured in different sizes with a variety of different lenses, reflectors, ballasts and lamps being available. The greater number of such fixtures have been made in width and length dimensions of 2'.times.4' and 2'.times.2' to be recessed to fit in a suspended ceiling. In these fixtures, each of the ballasts independently activates two fluorescent lamps connected in series. In most instances, one ballast controls the two outer lamps.
As a result of the "energy crisis"]and the ever increasing cost of electrical power generation, electrical energy users, including users of fluorescent lighting, have sought by various means to control their energy costs, e.g., by decreasing their electrical energy consumption. As a means to this end, users of fluorescent lighting have accepted reductions in illumination levels in various areas in office and factories where the reduction does not create an unacceptable level of light. A reduction in illumination is possible because in most instances, existing office and factory areas are overlit by present day lighting standards.
One particular method in the prior art of reducing illumination levels is by the removal of one or more lamps from a multi-lamp fluorescent fixture. In the case of a standard two-lamp fluroscent fixture, however, the two lamps are electrically connected in series; by removing one lamp the entire fixture is electrically disconnected. Consequently, "dead spaces"]are created in the areas the fixture was intended to illuminate. In a standard four-lamp fixture, in a manner similar to the two-lamp fixture, two lamps are electrically connected in series. If one lamp is removed, the connected second lamp is disabled, thus leaving the two other remaining lamps active and resulting in a 50% reduction in illumination. This type of arrangement, however, will result in an underdistribution of light. Moreover, an expected reduction in power consumption is not attained since the ballast associated with the two disconnected lamps is wired across the external power line to the fixture and consumes power even when the lamps are disconnected.
Other products comprising improvements in existing components of fluorescent lighting fixtures have been marketed as a further means for reducing energy lighting costs. For example, more energy efficient ballasts, see, e.g., "Ballasts for Fluorescent Lamps--Competitive Cross Reference," General Electric brochure, designated 20S-8068R, and fluorescent lamps, see, e.g., "Watt-Miser F40 Fluorescents", General Electric brochure, designated 205-9281 8/79 have become available. Further, in Jones U.S. Pat. No. 3,829,680 a plastic lighting panel is disclosed which minimizes ceiling reflections. In Westphal U.S. Pat. No. 3,956,665 a glass tube, the same shape and size of a fluorscent lamp, which encloses a capacitor within, produces no illumination but is installed in a standard lamp fixture in place of a fluorescent lamp. This arrangement permits both ballasts of a four-lamp two-ballast fixture to operate with the other three remaining lamps by converting the normal two-lamp ballast to a one-lamp ballast. What remains is a three-lamp fluorescent fixture operating on two ballasts.
Although a number of improved fluorescent lighting fixtures have become available, there is a need for a fluorescent lighting fixture which is more efficient than those products known to applicant, inexpensive, will extend the life of its major components, reduce maintenance and replacement costs, all without materially reducing the illumination produced to an unacceptable level. The invention is directed to providing a fixture meeting such needs.
One specific embodiment of the invention is a fluorescent lighting fixture which comprises a housing, a swinging door attached thereto including a lens, two ballasts, four standard fluorescent lamps and four corresponding pairs of lamp holders which support and engage the lamps. The fixture is controlled, for example, by a light switch which energizes both of the ballasts. It is usually the case that one ballast energizes the two outer lamps while the other energizes the two inner lamps. Two of the lamps, for example, the outer lamps, are removed and in place of each is inserted a reflecting assembly. Each reflecting assembly is comprised of a rigid reflecting surface and a cap at each longitudinal end thereof. The reflecting surface is variously configured, e.g., concave-convex along the longitudinal length of the remaining inner lamps, to redirect downwardly from said assembly to the areas intended to be illuminated, a substantial portion of the illumination received from the lamps remaining in the fixture which would otherwise be directed upwardly and be absorbed within the housing. The reflecting surface may be made from a highly reflective metal material, such as aluminum having a surface coating of anodic oxide. The caps are attached to the longitudinal ends of the reflective surface and may be made of a non-conductive flexible or plexiglass material. The total longitudinal length of the reflecting surface and caps is substantially equal to that of the fluorescent lamp which it replaces.
In operation, the selected lamp is removed and in its place is inserted the reflecting assembly. The caps are introduced into the respective lamp holders which support the assembly at both ends and are locked into place. The caps may be formed such that they do not contact the live elements of the lamp holder. The ballast which ordinarily powers, through the contact holders, the replaced lamps is optionally disconnected out of the circuit by removing the ballast leads, which in all instances is accessible to the user. This eliminates the power drain of the ballast even when the lamps have been deactivated.